1. Technical Field
The invention relates generally to a data processing system for processing pattern data and, more specifically, to a processor system for storing and processing pattern data in a high speed electron beam lithography system.
2. Background Art
Advances in modern microelectronics allow placing an increasing number of devices on a single integrated circuit base. One method of forming devices on an integrated circuit base is through electron beam (E-beam) lithography. In E-beam lithography, devices are generated on the circuit base through patterns that are processed in the pattern processing system of the E-beam system. The data used to generated the patterns of the devices is called pattern data. The typical pattern processing system of an E-beam lithography system comprises a controller, pattern storage device, buffer device and processor. The buffer device temporarily holds the pattern data from the pattern storage device until it can be processed and decoded by the processor.
One example of a typical pattern processing system is U.S. Pat. No. 4,698,509 "High Speed Pattern Generation for Electron Beam Lithography," issued to Wells et al. Wells et al. disclose a system that uses a random access memory (RAM) buffer for temporarily storing the pattern data. Custom hardware is used to decode the pattern data format specifically used for Wells' disclosure. The decoded pattern data is then used to generate the desired shape. Some disadvantages to using the system of Wells et al. are as follows: first, RAM buffers are typically large and expensive and, for storing patterns, consume a relatively large amount of power; second, unless the custom hardware is removed and redesigned, only the specified pattern data format may be decoded, and even then the new redesigned hardware is only set up for the new data format; and third, since there is no data compression in the system of Wells et al., extra space is being used in storing repetitive patterns.
Other typical pattern processing systems are found in the following U.S. Patents: U.S. Pat. No. 4,718,019 "Electron Beam Exposure System and an Apparatus for Carrying Out a Pattern Unwinder," issued to Fillion et al.; U.S. Pat. No. 4,280,186, "Exposure Apparatus Using Electron Beams," issued to Hidai et al.; and U.S. Pat. No. 5,005,138, "Electron Beam Direct Printing Apparatus," issued to Tobuse et al. Although these patents disclose an apparatus and process for storing and decoding pattern data, they use RAM buffers, which, as aforementioned, are large and expensive. Furthermore, they use custom hardware and/or software that is not reconfigurable for different decode formats "on-the-fly" (i.e., the hardware/software needs to be removed, redesigned and reprogrammed before another decode format may be used). Finally, the pattern data/elements are not compressed, thus wasting extra space.
Accordingly, a need has developed in the art for a pattern data processor that will efficiently and inexpensively store and process control pattern data.